A Primer on 356 Bearing Sets

Main bearings are a constant source of confusion for early air-cooled Porsche owners.  The Factory long ago stopped producing full sets and the engines can take a variety of different sizes, based upon year of manufacture and machine work to account for wear. Here's a handy guide to what bearings are available for your 356 or 912

The 356A and 356B were built with a three-piece engine case and a crankshaft with 50mm bearing journals.  The bearing sets for this engine are listed with 546 part number prefixes. 

The Super 90 (S90) came with a different crankshaft that had 55mm journals.  These bearing sets are numbered 616-100-130-XX (where XX varies based upon sizing).  While we do have the standard/standard size in stock, the sets for machined cranks are hard to source.

The 356C, SC and 912 engines had a 55mm crankshaft as well, but require a slightly different #1 bearing, These bearing sets are numbered in the 616-100-138-XX range.   

To fix wear issues, you can machine the crankshaft and use a correspondingly thicker bearing.  You can also line-bore the case to account for slight wear of the case. The naming conventions vary for this--some sheets have this  listed as case (outside)  / crank (inside)  and others are crank (inside) / case (outside).  Either way will work, as long as the part numbers match up to what you need.  The below chart has it case / crank.  

First machining is .25mm

Second machining is .50mm

Third machining is .75mm

Finally, our replacement main bearing sets typically use a modern steel-based bearing.  We've replaced the prefix of each SET with NLA and listed this in the name and description of each bearing set.   You can search on either the NLA- or 546/616 prefix to find what you need.  We have individual bearings that are the original aluminum style as well.